The present invention relates to a brushless DC motor drive, and more particularly to a method and system for determining an alignment error of a Hall sensor in such a drive, advantageously for optimizing the location of the Hall sensor.
Brushless DC motor drives commonly use Hall-effect sensors to determine rotor position. The Hall sensors sense the magnetic field of a magnet on the rotor, and produce a digital pattern indicating the rotor position in one of 6 possible sectors. Errors are introduced due to the relative mechanical locations of the Hall sensor and the magnet, the resolution and accuracy of the sensor, the pole width of the sense magnet, and the physical relationship between the sense magnet and the rotor. Because of these potential sources of error, the position measured by the Hall sensors may not exactly match the real rotor position. This position error can cause generation of lower torque at a given current.